Antimicrobial Activities of Bacteria Associated with the Brown Alga Padina pavonica

Abstract

Macroalgae belonging to the genus Padina are known to produce antibacterial compounds that may inhibit growth of human- and animal pathogens. Hitherto, it was unclear whether this antibacterial activity is produced by the macroalga itself or by secondary metabolite producing epiphytic bacteria. Here we report antibacterial activities of epiphytic bacteria isolated from Padina pavonica (Peacocks tail) located on northern coast of Tunisia. Eighteen isolates were obtained in pure culture and tested for antimicrobial activities. Based on the 16S rRNA gene sequences the isolates were closely related to Proteobacteria (12 isolates; 2 Alpha- and 10 Gammaproteobacteria), Firmicutes (4 isolates) and Actinobacteria (2 isolates). The antimicrobial activity was assessed as inhibition of growth of 12 species of pathogenic bacteria (Aeromonas salmonicida, A. hydrophila, Enterobacter xiangfangensis, Enterococcus faecium, Escherichia coli, Micrococcus sp., Salmonella typhimurium, Staphylococcus aureus, Streptococcus sp., Vibrio alginoliticus, V. proteolyticus, V. vulnificus) and one pathogenic yeast (Candida albicans). Among the Firmicutes, isolate P8, which is closely related to Bacillus pumilus, displayed the largest spectrum of growth inhibition of the pathogenic bacteria tested. The results emphasize the potential use of P. pavonica associated antagonistic bacteria as producers of novel antibacterial compounds.

Decoding Antioxidant and Antibacterial Potentials of Malaysian Green Seaweeds: Caulerpa racemosa and Caulerpa lentillifera

“…This is because there are studies that have reported that seaweed-associated bacteria play crucial roles in the development and growth of seaweeds, showing a symbiotic relationship between the bacteria and the seaweeds [89]. Another study found a potential broad-spectrum antibacterial effect from epiphytic bacteria (Phylum: Firmicutes; closely related to Bacillus pumilus ) isolated from brown seaweed Padina pavonica, thus suggesting that bacteria associated with seaweeds might be producers of antibacterial compounds [90]. Recently, a study by Sujuliyani et al [91] showed that C. racemosa has symbiotic bacteria belonging to the genus Neisseria that is able to synthesize potential antibacterial compounds against S. aureus and Salmonella typhi .…”

Antimicrobial Potential of Epiphytic Bacteria Associated With Seaweeds of Little Andaman, India

“…Besides these studies Karthick et al (2015b) had reported on antimicrobial activity of certain seaweeds against pathogenic bacterial and fungal stains. Several authors suggested that macro algal associated bacteria were found to be an efficient producer of antimicrobial compounds ( Burgess et al, 1999 ; Lee et al, 2006 ; Kanagasabhapathy et al, 2008 ; Karthick et al, 2015a ; Ismail et al, 2016 ). On the other hand, certain brown algae also produced biologically active compounds which inhibited the settlement of bacterial colonies on the thallus ( Nagayama et al, 2002 ).…”

Antimicrobial Lipids from Plants and Marine Organisms: An Overview of the Current State-of-the-Art and Future Prospects

“…A relationship was found among the antimicrobial activity against S. aureus, E. coli, and C. albicans, and the FA docosapentaenoic (DPA, 22:5) and triacylglycerol contents [121]. In the green macroalga Ulva rigida, purified fractions of crude extracts with the highest antibacterial activity against S. aureus and Enterococcus faecalis comprised mainly 16:0, 18:1, and 16:1 n-7 FA [27]. Nevertheless, most of these studies neither isolated the predominant FA nor tested its activity.…”

“…The antimicrobial activity efficiency may be conditioned by seasonal variation, that must be related with shifts in the lipid profiles promoted by alterations in growth-related environmental conditions [118]. Nevertheless, a seasonal variation was not always verified, like in the green seaweed U. rigida that demonstrated a uniform antimicrobial activity throughout the year [27].…”

“…Simultaneously, marine organisms, mainly slow-moving or sessile, have developed adaptive defense mechanisms to protect themselves against pathogenic microorganisms. In some cases, marine organisms maintain associations with microbiota, being bacterial symbionts responsible by the synthesis of antimicrobial molecules [ 26 , 27 ].…”